Presence is an indication of the availability of an individual at a point in time, and presently refers to the visibility of a person on a shared communication network.
A federated architecture allows interoperability and information sharing between information technology systems and applications. Presence services (PS), such as provided by Avaya Aura® Presence Services, provide an aggregated presence for a user. PS supports protocols, such as Session Initiation Protocol/Session Initiation Protocol for Instant Messaging and Presence Leveraging Extensions (SIP/SIMPLE) and Extensible Messaging and Presence Protocol (XMPP). PS uses server-to-server updates to collect and publish presence information, and may federate with third-party applications.
XMPP is utilized for both instant messaging (IM) and presence services (PS). A typical XMPP endpoint assumes that the same XMPP stream is used for both presence and messaging and utilizes the same server for both PS and IM.